Larry Bates wrote:
> def CalculateCrc(buffer, crc):
/snip/
> The algorithm looks very much like the source code for
> binascii.crc32 (but I'm not a C programmer).
does your Python version give the right result ? if so, the following
might be somewhat helpful:
def test1(text, crc=0):
# larry's code
result = CalculateCrc(text, crc)
return hex(result[0])
def test2(text, crc=0):
import Image
# using pil's crc32 api
a = (crc >> 16) ^ 65535
b = (crc & 65535) ^ 65535
a, b = Image.core.crc32(text, (a, b))
a ^= 65535
b ^= 65535
return "0x%04X%04XL" % (a, b)
def test(text):
print test1(text), test2(text)
test("hello")
test("goodbye")
this prints
0xF032519BL 0xF032519BL
0x90E3070AL 0x90E3070AL
no time to sort out the int/long mess for binascii.crc32, but it pro-
bably needs the same tweaking as PIL (which handles the CRC as
two 16-bit numbers, to avoid sign hell).
</F>
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